Conventional magnetic heads typically employ lapping to fabricate structures within the head. In order to control lapping an electronic lapping guide (ELG) is typically used. FIG. 1 depicts a top view of a conventional ELG 10. The conventional ELG 10 is essentially a resistive stripe. Thus, the conventional ELG 10 is coupled with pads/leads 14 and 16 that are used to provide electrical connection to the conventional ELG 10. Using the pads/leads 14 and 16 the resistance of the conventional ELG 10 may be determined. The conventional ELG has a length l from the surface 12 being lapped. As lapping continues, the surface 12 is worn away, and the length of the conventional ELG 10 decreases. As the length is reduced, the resistance of the conventional ELG 10 increases. Using the resistance of the conventional ELG 10, it can be determined when lapping should be terminated.
For example, energy assisted magnetic recording (EAMR) transducer is typically lapped during fabrication. A conventional EAMR transducer includes not only magnetic components, such as poles, coils, and shields, but also energy-delivery components. An EAMR transducer may include optical components gratings, waveguides and near-field transducers (NFTs). FIG. 2 depicts a portion of a conventional NFT 20. A conventional NFT 20 typically includes a disk portion 22 and a pin portion 24. The disk portion 22 is wider in the direction parallel to the air-bearing surface (ABS) than the pin portion 24. Lapping may be used to control the length, l, of the pin portion 24 of the NFT, as well as other lengths such as the throat length of the pole (not shown in FIG. 2).
FIG. 3 is a flow chart depicting a conventional method 30 for performing lapping using the conventional ELG 10. The lapping performed in the method 30 may be used in fabricating the conventional NFT 20. The resistance of the conventional ELG 10 is measured during lapping of the transducer, via step 32. The current length of the conventional ELG 10 is determined based upon the resistance measured in step 32 and the sheet resistance of the conventional ELG 10, via step 34. Thus, after step 34, the length corresponding to a particular measured resistance for the conventional ELG 10 is known. Alternatively, step 34 could simply convert a desired length of the pin portion 24 to an ELG length and the ELG length to a desired target resistance of the conventional ELG 10.
The lapping is terminated when the resistance of the conventional ELG 10 indicates that the desired length or target resistance of the conventional ELG 10 has been reached, via step 36. Because the conventional ELG 10 and structure, such as a read sensor or pole, both exist on the transducer being lapped, the lengths of the conventional ELG 10 and the structure change with lapping. Consequently, the lengths of the read sensor or pole may also be set in step 36.
Although the conventional method 30 and conventional ELG 10 function, the desired length of the NFT may not be easily controlled to the desired length. The dimensions of the conventional NFT 20 are desired to be carefully controlled. For example, the distance between the disk portion 22 of the NFT 20 and the ABS (i.e. the length of the pin portion 24) is desired to be closely controlled. Such control may be difficult to achieve using conventional manufacturing and lapping methods. Thus, fabrication of the conventional EAMR transducer may be challenging.
Accordingly, what is needed is an improved method for providing and using an ELG in a magnetic transducer such as an EAMR transducer.